A hybrid vehicle powertrain may deliver torque to propel a vehicle via a piston engine or an electric machine. The electric machine may be beneficial to reduce vehicle fuel consumption during vehicle launch from zero speed or a low speed to a higher speed. The piston engine may be activated when higher torque demands are requested and to increase the vehicle's driving range. Nevertheless, operating the piston engine may not be desirable during conditions where a traction motor is capable of providing nearly as much torque as is desired because the piston engine is less efficient than a traction motor. Further, although it may be possible to provide additional electric machines to increase driveline torque and delay piston engine starting, the cost of additional electric machines may be prohibitive. Additionally, it may be increasingly difficult to provide smooth powertrain torque when multiple torque sources are combined.
The inventors herein have recognized the above-mentioned disadvantages and have developed a hybrid vehicle powertrain, comprising: a piston engine; an electric machine; a turbine engine located along an exhaust passage of the piston engine; and a planetary gear set mechanically coupled to the piston engine, the electric machine, and the turbine engine.
By combining torque from an electric machine, the piston engine, and the turbine engine and delivering the torque via a planetary gear set, it may be possible to provide the technical result of providing various levels of powertrain torque. Further, the torque may be provided in a smooth progressive manner without having to have to provide sophisticated clutch torque control. Additionally, the turbine engine may be incorporated as part of a turbocharger to decrease system cost and complexity.
The present description may provide several advantages. In particular, the approach may provide smooth powertrain torque from a plurality of torque sources. Additionally, the approach may provide for additional levels of powertrain torque production. Further, the approach may eliminate the need for complex clutch control algorithms.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.